802.5 IEEE Standard

The IEEE 802.5 standard specifies the characteristics for Token Ring networks. Token Ring was introduced by IBM in the mid-1980s and quickly became the network topology of choice until the rise in popularity of Ethernet. It is unlikely that you will encounter a ring network in your travels and even more unlikely that you will be implementing a ring network as a new installation. For what it's worth, Token Ring is a solid network system, but Ethernet has all but eliminated it.

The following is a list of the specific characteristics specified in the 802.5 standard:

  • Speed The 802.5 Token Ring specifies network speeds of 4 and 16Mbps.

  • Topology Token Ring networks use a logical ring topology and most often a physical star. The logical ring is often created in the multistation access unit (MSAU).

  • Media Token Ring networks use unshielded twisted pair cabling or shielded twisted pair.

  • Access method 802.5 specifies an access method known as token passing. On a Token Ring network, only one computer at a time can transmit data. When a computer has data to send, it must use a special type of packet known as a token. The token travels around the network looking for computers with data to send. The computer's data is passed along with the token until it gets to the destination computerat which point, the data is removed from the token and the empty token placed back on the ring.